This invention relates to an internal combustion engine having a compact configuration and more particularly to an oil pump drive arrangement for such an engine.
In conventional engine constructions utilized for powering motor vehicles, a number of engine auxiliaries and accessories are driven from the crankshaft through a wide variety of types of drive mechanisms. For example, in modem high performance internal combustion engines, the engine is provided with twin overhead camshafts for directly operating the valves of the associated cylinder block. These camshafts are driven obviously from the crankshaft through a camshaft drive mechanism.
Many other engine auxiliaries are also driven off of the engine crankshaft, either directly or indirectly. In many instances, these auxiliaries are driven off of pulleys that are mounted on the ends of the crankshaft and which are disposed outwardly of the cam driving mechanism. This, obviously, adds to the overall length of the engine. This can present substantial problems with engine installation in the vehicle. This particularly true if the engine is mounted in a transverse direction in the engine compartment.
There has been proposed, therefore, a type of engine wherein the camshaft drive and overall construction is somewhat simplified by utilizing an intermediate shaft that is driven off of the engine crankshaft and which drives one or more accessories. This invention relates to an improvement in engines of this type.
One of the accessories which must be driven is the oil pump. If the oil pump is driven off of the intermediate shaft rather than directly off of the crankshaft, then the overall arrangement can be simplified to some extent and also the drive for the oil pump need not be positioned at the end of the engine. However, it is also generally the practice to have the intermediate shaft disposed at an elevation that is generally above that of the crankshaft and, hence, is above the crankcase. Although is no problem is the engine is provided with a dry sump system, the oil pump drive and oil pump location can present problems when the engine is of the wet sump type.
It is, therefore, a principal object of this invention to provide an improved oil pump drive arrangement for an internal combustion engine.
It is a further object of this invention to provide an improved internal combustion engine having an intermediate shaft for driving accessories and an improved method for driving the oil pump from such an intermediate shaft.
It is a further object of this invention to provide an improved intermediate shaft oil pump drive for an engine that permits the oil pump to be positioned closer to the crankcase of the engine.
As is generally known, many of the accessory drives for an engine employ flexible transmitters such as belts and/or chains. These mechanisms have a number of advantages over gear trains, particularly in the area of noise. However, in conjunction with driving an oil pump, it is desirable to ensure that the pump drive is more positive, and hence gear drives are normally employed for driving the oil pump.
In engines having intermediate shafts of the type generally described, the intermediate shaft is normally driven from the crankshaft by means of a gear drive. In order to provide a better drive and a somewhat more silent drive, it has been the practice to employ bevel or helical gears for this purpose. A disadvantage of the use of helical gears is, however, that is places an axial force on the shafts, and thrust bearings must be employed for taking the axial thrust so generated.
It is, therefore, a still further object of this invention to provide an improved oil pump drive arrangement wherein the oil pump drive is such that the driving thrusts on the driving shaft are balanced to minimize the need for thrust bearings.